feat: allow to set your local timezone in settings and provide it to clients

[susnux]

• Resolves: Create a centralised setting for users to set their timezone #51026

Summary

1. Move timezone configuration of user to the personal settings instead of calendar availability
2. Provide timezone as current users capability so we can use it in clients and frontend

IMHO this makes it much easier to discover setting the timezone of oneself.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[skjnldsv]

I do wonder if there isn't a part missing regarding the sync of the property with federation. This is quite a mess, but I do remember some area I had to touch when adding the pronouns that I don't see here 🤔
Worth double checking 😊

[ChristophWurst]

\OC\Authentication\Login\SetUserTimezoneCommand still sets the timezone at login and potentially overwrites what the user has set manually. Should the login chain command perhaps only set the timezone value when it hasn't been set before?

[susnux]

Should the login chain command perhaps only set the timezone value when it hasn't been set before?

Yes this makes sense, but we still need the login timezone in the session.
Added this as a new commit.

[ChristophWurst]

Looks good!

Could you add a test case for the existing timezone to \Test\Authentication\Login\SetUserTimezoneCommandTest please?

[ChristophWurst]

Could you add a test case for the existing timezone to \Test\Authentication\Login\SetUserTimezoneCommandTest please?

Nvm, you pushed that a minute ago 😄

[susnux]

Nvm, you pushed that a minute ago 😄

Yes sorry I just squashed the fixup of it 🙈